This invention relates to an identification of an artificial object and, especially, identifying an artificial object by a sensor which can measure capacitance. Further, this invention relates to an artificial object used therein.
It is an ordinary practice to seal documents as an approval in Japan and People's Republic of China and the like. E-document Law went into effect in Japan in April 2005. The E-document Law permits companies to electronically store the documents which are legally required to retain, such as financial documents, accounting records and tax documents.
Japanese Patent Application Laid-Open No. 2002-300157 describes the electronic seal stamp system including an electronic seal stamp provided with a storage means that stores particular ID number information, with a means including the ID number information onto an electromagnetic wave, and with a means that transmits the electromagnetic wave including the ID number information. Japanese Patent Application Laid-Open No. 2012-118637 describes an authentication system including a tablet type computer using a capacitance system touch panel, and an electronic seal which can input identification information comprised of a capacitance variation in the tablet type computer.
U.S. Pat. No. 7,683,888 describes a system and method for recognizing a signet and for performing an action associated with the signet, wherein the signet is an inanimate object, and the method includes generating a touch signal with a signet, the touch signal representing a particular signet pattern, recognizing the particular signet pattern, and performing an action associated with the particular signet pattern.
However, both of the electronic seal stamps described in Japanese Patent Applications Laid-Open Nos. 2002-300157 and 2012-118637 need power supplies and electrical circuits inside a seal and they are costly. Further, it is undesirable that signets can be easily duplicated by referring signet patterns, which causes a security problem, in the invention described in U.S. Pat. No. 7,683,888.